Automatic brake



g 1942- A. w. WIGGLESWORTH 2,293,375

AUTOMATIC BRAKE Filed May 17, 1941 3 Sheets-Sheet l 8. 2- A. w.WIGGLESWORTH 7 AUTOMATIC BRAKE 3 Sheets-Sheet 2 Filed May 17, 1941 g 9A. w. WIGGLESWORTH 2,293,375

AUTOMATIC BRAKE wamnzwl m 5M6 & 73

Patented Aug. 18, 1942 UNETED STATES earns? OFFICE AUTOMATIC BRAKEApplication May 17, 1941, Serial No. 393,919

3 Ciaims.

This invention relates to automatic brakes, and particularly to brakesfor automatically stopping the rotation of motor driven revolving workheadstocks.

My invention especially adapted for and herein shown as applied to agrinding machine headstock such as is shown and described in my UnitedStates Letters Patent No. 2,095,089, but obviously the automatic brakeof my invention may be applied to many other machines in which it isdesired to automatically instantly stop the rotation of motor drivenrevolving shafts or parts.

The main object of the invention isto provide a brake mechanism whichautomatically frictionally engages the motor driven shaft or part to berendered motionless, simultaneously with the cutting oif of the electriccurrent to the motor, said brake mechanism being automatically releasedwhen the motor is started.

Heretofore, in the operation of grinding machines having motor drivenheadstocks, the momentum of the motor shaft and the shafts driventhereby was such as to cause the work to be revolved for some momentsafter the motor current had been cut off, resulting in substantial lossof time in removing the finished work. By means of the brake mechanismherein disclosed, the rotation of the motor driven shaft and the work isautomatically stop d simultaneously with the operation of the swi. hwhich cuts off the motor current. Consequently the finished work can beremoved and new work mounted in the machine without loss of time.

In the drawings:

Fig. l is a front elevation of the headstock end portion of a grindingmachine to which my automatic brake has been applied.

Fig. 2 is a rear elevation, partly in section, taken in the plane of theline 2-2 of Fig. 3.

Fig. 3 is an end elevation, partly in transverse vertical section, takenin the plane of the line 3-3 of Fig. 1.

Fig. 4 is a diagrammatic view of the automatic brake and motor circuitof my invention.

Fig. 5 is an elevational view of the brake mechanism, on an enlargedscale, the casing being in section.

Fig. 6 is a plan view, partly in section, of the brake mechanism, thesection being taken in the 5 plane of the line 5-5 of Fig. 5.

Fig. 7 is a plan view of the right hand portion of the brake mechanismas shown in Fig. 5.

In that embodiment of the invention shown in the drawings, my automaticbrake is applied to the change speed pulley shaft of the motor drivenheadstock of a grinding machine. The machine comprises a base El,longitudinally movable work carriage II, headstock housing 12, motor andpulley housing [3, work holding spindle i4, and change speed pulley 45on shaft l5. Within the housing i3 is a motor it which drives the shaftI 6 through the pulley E8 on shaft [9. A handle 25 is rigidly connectedto the housing l2 and is used to move the housing p-ivotally about thepoint 2! when it is desired to lower or raise the change speed pulley l5and shaft 6 for the purpose of adjusting the belt 22 on said changespeed pulley, as shown in Figs. 2 and 3.

From the foregoing it will be understood that the motor I! drives theshaft 55 through the pulley l8, shaft i9 and belt 22, and that the shafti6 is operatively connected, through means in the housing l2, with thework. revolving part of the headstock. The brake mechanism about to bedescribed is mounted in such manner that it engages and disengages theshaft i5 and thus controls the spindle M.

The automatic brake mechanism of my invention is mounted on a plate 23which is secured by the bolt 24 to the headstock housing l2 so as tomove with the housing when the latter is moved, as explained, foradjustment of the belt 22 on the change speed pulley l5. The pulleyshaft l6 extends through the plate 23 and has a brake drum 25 fixed onits free end by a set screw 26, as best shown in Figs. 5 and 6. Thebrake drum 25 is adapted to be frictionally engaged by a pair of brakebands or curved arms 21, 21, provided with brake linings 28, 28, whichembrace the upper and lower peripheral surfaces, respectively, of thebrake drum 25 on shaft H5. The brake bands 21 are cut away vertically atone end to provide eyeletted members 29, 29 narrower in width than thebands proper, so that said members 23 can be mounted pivotally, in axialalignment, on the bolt 24. Thus the bands 21 are vertically aligned andmovable toward and away from each other about the pivotal point 24.

The brake bands 21, at their ends opposite the pivotal mounting 24, havearms 30 which are spaced apart and substantially parallel with eachother, and provided with oppositely inclined surfaces 3| on theirproximate inner surfaces. A bolt 32 extends through apertures in saidarms 30 adjacent the bands 21, and coiled springs 33 compressed betweenthe nuts 34 and arms 30 tend to urge the arms 39 toward each other andnurses thereby move the brake bands 21-28 into braking position on thedrum 25., as shown in Fig. 5.

The means for moving the brake bands into non-braking position comprisea spacer block 35 and yoke 35' in which are mounted roller bearings 35,said yoke being pivotally connected by a pin 31 to a plunger 38 actuatedby a solenoid 39 fixedly mounted on the plate 23. The solenoid iselectrically connected in the circuit of the motor H, as indicated inFig. 4. When the solenoid is energized, that is, when the switch 40 isclosed, and the motor I! is running, the plunger 38 is retracted by thesolenoid and the spacer block 35 is drawn toward the freeends of thearms 3%, causing the bearings 36 to engage the inclined surfaces 3! andforcing the arms 30 apart and the brake bands 2l28 away from the drum25. off and the solenoid is de-energized, as when the switch 49 is open,as shown in Fig. l, the parts assume the position shown in Figs. 5 and6, wherein the springs 33 have urged the arms 36], 30 toward each otherand caused the spacer bearings 36 to move inwardly from the free ends ofthe arms 39.

The operation of the brake will be understood from the foregoingdescription. When the Work revolving part of the headstock is beingdriven by the motor I! through intermediate shaft IE, the solenoid willbe energized and the brake bands 21-48 will be inoperative, butinstantaneously after the motor current has been cut oil by actuatingthe switch 53, the brake bands automatically embrace the drum 25 (orother part with which they may be associated) and stop the rotation ofthe shaft l6 and of the work revolving part of the headstock.

The brake mechanism may be covered by a guard M which cooperates withthe plate 23 to enclose the parts.

Changes may be made in details of construction without departing fromthe scope of my invention.

I claim:

1. The combination of an electric motor driven headstock including aheadstock housing, a revolving shaft extending through said housing androtatably connected to said headstock, a brake mechanism mounting plateconnected to the housing by means including a bolt, said revolving shaftextending also through the plate, a brake drum on one end of said shaft,brake mechanism pivotally mounted on said bolt in position to embracethe drum, a solenoid mounted on the plate and electrically connected inthe motor circuit, means actuated by the solenoid to move the brakemechanism to non-braking position relatively to the drum when thesolenoid is energized by the motor current, and means mounted on thebrake mechanism for moving said mech- When the motor I l is out anism tobraking position when the solenoid is de-energized, the headstockhousing being pivotally mounted about the horizontal axis of theheadstock.

2. The combination of an electric motor driven headstock including aheadstock housing and a work holding spindle extending through saidhousing, a revolving shaft driven by the motor and rotatably connectedto said headstock, a brake mechanism mounting plate connected to thehousing to one side of said spindle, said revolving shaft extendingthrough the plate, a brake drum on one end of said shaft, a change speedpulley on the other end of the shaft, brake mechanism pivotally mountedon said plate in position to embrace the drum, a solenoid mounted on theplate and electrically connected in the motor circuit, means actuated bythe solenoid to move the brake mechanism to non-braking positionrelatively to the drum when the solenoid is energized by the motorcurrent, and means mounted on the brake mechanism for moving saidmechanism to braking position when the solenoid is de-energized, saidplate with the brake mechanism mounted thereon and said headstockhousing being pivotally movable about the horizontal longitudinal centerof said spindle.

3. In combination with an electric motor and a motor driven revolvingshaft, brake mechanism for automatically arresting rotation of the shaftwhen the motor current is cut off, said brake mechanism comprising abrake drum secured to the shaft, a pair of drum engaging brake bandspivotally connected adjacent the periphery of said drum and at one sideof said shaft, said brake bands including arcuate drum engaging portionsand elongated substantially parallel arms at the opposite side of saidshaft, said arms having opposed surfaces oppositely inclined outwardlyfrom their free ends toward said drum, a solenoid electrically connectedto the motor circuit and having its axis in the central plane of saiddrum and substantially in a line extending through the axes of saidshaft and pivotal connection, a spacer disposed between said arms andprovided with rollers engaging said inclined surfaces, a plungerconnected with said solenoid and pivotally connected with said spacer, abolt extending through said arms between said drum and spacer, andsprings in compression between nuts on opposite ends of the bolt andsaid arms for moving said brake hands into braking engagement with saiddrum and through said inclined surfaces moving said spacer toward saiddrum when the motor current is cut off, said spacer being moved awayfrom said drum through energization of said solenoid when the motorcurrent is turned on to move said bands away from said drum.

ALBERT W. WIGGLESWORTH.

